A conventional light emitting display of a 7-segment structure has a configuration shown in FIG. 6A, which is a perspective explanatory view, and in FIG. 6B, which is a cross-sectional explanatory view, taken along a line B-B of FIG. 6A. Specifically, a light guide 13a constituting 7 segments is formed at a reflecting case 13. A light emitting diode (hereinafter, abbreviated as “an LED”) chip 12 is die-bonded to a lead 11 with respect to each of the segments. The LED chip 12 is wire-bonded via a gold wire 121 or the like, and then, a translucent or transparent resin (resin passing through the light) 14 is filled into the light guide 13a. The LED has an anode and a cathode. Although two leads are required for each of the segments, the lead of either one of the anode and the cathode can be commonly used by the segments. Eight to ten leads form a numeral of one digit (inclusive of leads for displaying a decimal point), and the plurality of leads 11 are disposed along two long sides in a vertical direction (that is, both of lateral sides in a displaying direction) or on both sides in a vertical direction.
The inside of the above-described light guide 13a needs to be a light reflective color based on a white color in order to emit light emitted from the LED 12 as brightly as possible at the segment, and therefore, the reflecting case is normally resin-molded with a white plastic. In order to easily recognize a display color of each of the segments, a surface of the case B of display side is coated with a dark color such as black. This black coating is applied by screen printing with an black ink, followed by drying (see, for example, Japanese Published Unexamined Application No. 2002-182589).
In the meantime, an illumination signboard has been known as a device for displaying a predetermined image or letter such as advertisement or a guide display plate at a station or the like, unlike an LED dot matrix display device or a liquid crystal display device in which a display image are changed at any time. In the illumination signboard, a light source such as a fluorescent tube 51 serving as a backlight is housed inside of a reflecting case 52, and further, a display panel 54, on which an image is formed, is disposed at the surface of the backlight via a light diffusing plate 53, so that an image formed on a display film is lighted up, as shown in, for example, FIG. 7.
With the above-described configuration in which the fluorescent tube is used as the backlight, a uniform display image cannot be formed due to the appearance of the fluorescent tube since it is too bright near the fluorescent tube 51 while it is too dark apart from the fluorescent tube 51 unless a distance between the fluorescent tube 51 and the display panel 54 is set large, thereby raising a problem of a large size of the device with a great depth (see, for example, Japanese Published Unexamined Application No. 8-153405).
In order to solve the above-described problem, as shown in FIG. 8, there has been known a configuration in which light is guided from a side surface of a light guiding plate 61 by using a linear light source 62 having a fluorescent tube or light emitting diodes (i.e., LEDs) which are arranged linear like, or a dotted-like light source, and further, a display panel 64 on which an image is formed, or a liquid crystal panel is disposed at the upper surface. In this configuration, a plane-like light source for uniformly radiating light via a light diffusing plate 63 disposed at the surface of the light source is used as a backlight, so as to display the image on the display panel or the liquid crystal panel (see, for example, Japanese Published Unexamined Application No. 8-153405). In this case, a light reflecting film may be provided at the reverse or side surface of the light guiding plate, or a reflecting film pattern different in size may be formed at the reverse of the light guiding plate in order to make luminance at the surface uniform.
As described above, in the light emitting display device for the numeral or the like, the reflecting case is formed with a white plastic, and further, its surface of display side is coated with a dark color such as black. However, although in case that the device is used for a fee display at a normal vending machine or a time or a guide displayed on a destination list at a station, only the display of numerals or letters consisting of 7 segments in red in a dark color background is sufficient, in case that gorgeousness is required for a play machine such as a pachinko machine or a slot machine, it raises a problem of poor attraction in a simple display in the dark color background.
Moreover, in changing the color of a background in the conventional 7-segment display, a color to be applied to the surface of the reflecting case can be replaced with a showy color, but there are few variations by only changing the color of the reflecting case since the color is the same at all times. In view of this, in order to change the color of the background, it is necessary to dispose LEDs for the color of the background inside of the case partitioning the segments. However, since the case is molded with the resin, as described above, some thickness is required for fabricating the case without any deformation of the case (in particular, any degradation of the flatness of the surface), and further, a clearance for relieving a stress is also required, thereby making it impossible to additionally dispose the LEDs from the viewpoint of a space.
In addition, it may be constructed that, for example, LEDs are disposed on a portion corresponding to the display of the 7 segments and other portions on a substrate, and only the portion corresponding to the display of the 7 segments is partitioned with a cover for allowing all of the segments to emit light, respectively; and the display image and the background are lighted in different colors. However, it is necessary to dispose LEDs in divided non-displays, respectively. In particular, LEDs of red (R), green (G) and blue (B) are required for each of the non-displays in order to display the background in full colors. This markedly increases the number of LEDs, thereby leading to an increase in cost. Moreover, if the display image and the background color are lighted at the same luminance, it is difficult to identify the display image, so it arises an attendant problem that a drive circuit needs to be independently disposed.
On the other hand, as described above, in the case where a display image, which is not changed, is displayed by lighting up or the like, a clear display image is lighted up, to achieve a display of a good appearance by directly irradiating the display panel having an image formed thereon from the reverse thereof by a light source or irradiating the display panel by the backlight which is a uniform plane-like light source using a light guiding plate. However, in the case of the direct irradiation, the distance between the light source and the display panel must be enlarged, thereby increasing a size. Further, in the case of using the light guiding plate there has arisen a problem of an increase in cost. Additionally, the image is not directly displayed with the light emitted from the light source in any of the methods, but the display panel is lighted up. Therefore, the light emitted from the light source is indirectly used in much vain with much consumption of electric power, thereby raising a problem of an increase in cost.
Moreover, in the case of, for example, a simple guide display such as “Emergency” in a building or “Entrance” or “Exit” inside of a public building or a simple display advertisement plate, it is desirable to achieve as attractive a display as possible at a reduced cost in thin shape with low consumption of electric power.